Today, even normal locomotion is difficult to master for people who depend on prostheses or exoskeletons for mobility and rehabilitation, and there is a clear understanding in the wearable robotics community that a more interactive control of artificial limbs will be required than is common today to overcome this limitation. This project embraces such an interactive control. A cyber-physical approach to control is pursued, in which the artificial limb takes advantage of rich sensory information to continuously reason about and adapt its behavior to both the user and the environment in a way that improves locomotion stability, robustness and versatility. The specific aims of the proposed research are to establish this cyber-physical approach for artificial limbs, to develop multi-sensory and highly dynamic prototype exoskeletons and prostheses that enable its sensor-rich and data-intensive implementation, and to evaluate the resulting controller benefits in human subject experiments. The project combines two teams who will integrate their complementary expertise in legged dynamics and control, state estimation and learning, sensor fusion, mechatronic design, real-time control, and gait analysis to achieve these aims. The long-term goal of this research is to improve the quality of life for people who depend on artificial limbs for mobility and gait rehabilitation, with target populations ranging from lower limb amputees to stroke and spinal cord injured patients to older adults requiring mobility aids. The project directly relates to the NIBIB mission of improving health by development and acceleration of biomedical technologies. In particular, with its focus on next generation human-robot systems for improving gait assistance and rehabilitation, the project addresses NIBIB's strategic goal of developing innovative biomedical technologies that integrate engineering with the physical and life sciences to solve complex problems and improve health. RELEVANCE (See instructions): This project investigates the scientific foundation and related enabling technologies for intelligent, lower limb prostheses and exoskeletons that improve gait mobility and assistance by adapting their behavior to the human user intent and the environment. Populations likely to benefit from such advanced assistive devices include lower limb amputees, stroke and spinal cord injured patients, and older adults requiring mobility aids.